32 bit Instruction Word (IW) of SimpleCPU:
i=1 implies B is Immediate (meaning a number) as opposed to a Pointer (meaning Address)
Instruction Set of SimpleCPU:
ADD -> unsigned Add
{opcode, i} = {0, 0}
*A <- (*A) + (*B)
write (readFromAddress(A) + readAddress(B)) to address (A)
*A = value (content of) address A = mem[A] (mem means memory)
*B = value (content of) address B = mem[B]
<- means write (assign)
mem[A] = mem[A] + mem[B]
mem[IW[27:14]] = mem[IW[27:14]] + mem[IW[13:0]]
ADDi -> unsigned Add immediate
{opcode, i} = {0, 1}
*A <- (*A) + B
B = read section B of the Instruction
mem[A] = mem[A] + B
mem[IW[27:14]] = mem[IW[27:14]] + IW[13:0]
NAND -> bitwise NAND
{opcode, i} = {1, 0}
*A <- ~((*A) & (*B))
{opcode, i} = {0, 1}
NANDi -> bitwise NAND immediate
{opcode, i} = {1, 1}
*A <- ~((*A) & B)
SRL -> Shift Right if the shift amount (*B) is less than 32, otherwise Shift Left
{opcode, i} = {2, 0}
*A <- ((*B) < 32) ? ((*A) >> (*B)) : ((*A) << ((*B) - 32))
SRLi -> Shift Right if the shift amount (B) is less than 32, otherwise Shift Left
{opcode, i} = {2, 0}
*A <- (B < 32) ? ((*A) >> B) : ((*A) << (B - 32))
LT -> if *A is Less Than *B then *A is set to 1, otherwise to 0
{opcode, i} = {3, 0}
*A <- ((*A) < (*B))
LTi -> if *A is Less Than B then *A is set to 1, otherwise to 0
{opcode, i} = {3, 1}
*A <- ((*A) < B)
CP -> Copy *B to *A
{opcode, i} = {4, 0}
*A <- *B
CPi -> Copy B to *A
{opcode, i} = {4, 1}
*A <- B
CPI -> (regular) Copy Indirect: Copy **B to *A
(go to address B and fetch the number then treat it as an address and go to that address and get that data and write to address A)
{opcode, i} = {5, 0}
*A <- *(*B)
write (readFromAddress(readFromAddress(B))) to address (A)
CPIi -> (immediate) Copy Indirect: Copy *B to **A
(go to address B and fetch the number (*B) then go to address A and fetch the number there and treat it as an address and write there *B)
{opcode, i} = {5, 1}
*(*A) <- *B
write (readFromAddress(B)) to address (readFromAddress(A))
BZJ -> Branch on Zero
(Branch to *A if *B is Zero, otherwise increment Program Counter (PC))
{opcode, i} = {6, 0}
PC <- (*B == 0) ? (*A) : (PC+1)
if(*B == 0) goTo(*A), else goTo(nextInstruction)
BZJi -> Jump (unconditional branch)
{opcode, i} = {6, 1}
PC <- (*A) + B
MUL -> unsigned Multiply
{opcode, i} = {7, 0}
*A <- (*A) * (*B)
MULi -> unsigned Multiply
{opcode, i} = {7, 1}
*A <- (*A) * B